Metal ion complexes with DNA bases, blocked bases (e.g., 9-N-methyladenine) mononucleotides, di- and tri nucleotides have either been synthesized or shall be synthesized. The metal ions under consideration are: Cu (II), Co (II), Ni (II), Mn (II), Pt (II), Pd (II) and various compounds with these ions. The complexes will be characterized by standard techniques such as visible-uv spectra, esr and NMR where applicable. In appropriate situations the crystal structure will be determined to locate the site of metal ion attachment, the local stereochemistry and the effect of complex formation on the base geometry. These results will help lead to an understanding of the mechanism of metal ion inhibition of DNA synthesis by particular Pt ion 2 complexes as well as the mechanism of DNA stabilization or destabilization by metal ions.